<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            margin: 0px;
        }
        header {
            height: 200px;
            background: #ffc;
        }

        nav {
            height: 50px;
            background: #cff;
        }

        #left {
            width: 70%;
            background: #fcf;
        }

        #left,
        aside {
            float: left;
        }

        section {
            height: 300px;

        }

        aside {
            width: 30%;
            height: 600px;
            background: #ffc;
        }

        footer {
            height: 300px;
            background: #333;
        }

        .clear {
            clear: both;
        }
    </style>
</head>
<body>
<div id="container">
    <header>header</header>
    <nav>nav</nav>
    <div id="content">
        <div id="left">
            <section>section 1</section>
            <section>section 2</section>
        </div>
        <aside>aside</aside>
        <div class="clear"></div>
    </div>
    <footer>footer</footer>
</div>
</body>
</html>